Field of the Invention
The present invention relates to a sheet feeder device that conveys a transfer medium, and an image forming apparatus including the sheet feeder device.
Description of the Related Art
In an image forming apparatus that forms an image on a transfer medium and performs printing, a paper sheet is supplied for printing from a sheet feeder device that stores paper sheets. In the sheet feeder device, a sheet feed tray is disposed in a sheet feeding position so that paper sheets are supplied.
In the image forming apparatus, an image is formed on a paper sheet called a long paper sheet in some cases. Unlike a standard paper sheet such as A3 paper or A4 paper, the long paper sheet is long in a predetermined direction. There are long paper sheets having various lengths, such as 660 mm, 750 mm, and 1200 mm. Particularly, there is an increasing demand for mass-printing on long paper sheets up to 660 mm in length these days. To supply a long paper sheet with a low frequency of use, it is necessary to prepare a sheet feeder device that is longer in size than the long paper sheet to be used. Such a sheet feeder device might fail to appropriately store A3 and A4 paper with a high frequency of use.
To counter this, an opening is formed at an upper portion of a conventional sheet feeder device, and a lid is provided to cover the opening. The sheet feeder device includes an elevating means to lift a sheet feed tray up and down in the sheet feeder device main unit. When the lid is located on the upstream side of the upper opening in the conveying direction and forms an obtuse angle with the tray, a long paper sheet that is longer than the tray can be loaded onto the tray and the lid (see JP 2010-143736 A).
In this conventional structure, the opening direction of the lid can be changed, and the elevating tray can be prevented from moving down from the sheet feeding position by a user operating a component related to the lifting up and down of the tray. By this technology, a large number of paper sheets with a high frequency use can be stored, and a long paper sheet that is not frequently used but has a great sheet length can be used while an increase in the size of the machine is prevented.
By the conventional technology, the lowering position of the elevating tray is changed by controlling the opening direction of the lid. However, the user needs to switch the opening direction of the lid when loading paper sheets onto the elevating tray, and needs to switch elevating drive joints or the like, resulting in a troublesome operation. Furthermore, in a case where the lid is opened in a wrong direction, the tray is not lowered even when the user wishes to load a large number of paper sheets onto the tray, or the tray is lowered too far, and a long paper sheet is bent or wrinkled though the user wishes to load the long paper sheet onto the tray.
Furthermore, the lid that covers the opening at the upper portion is also used as the sheet loading means. As a result, while paper sheets are being supplied, the lid might come into contact with a rotating member such as the drive roller for supplying paper sheets, and safety might be undermined.